Self propelled saw

ABSTRACT

A concrete saw is provided having an engine aligned along a longitudinal axis of the saw frame to minimize the width of the saw and provide a more balanced system. A clutch assembly is attached to a forward end of the engine to disengage the saw blade without stopping the engine. A right angle gear box is provided proximate the driven side of the clutch assembly to transfer driving rotational forces from the engine to a transversely aligned driven shaft. The driven shaft includes drive pulleys mounted upon opposite ends thereof, which are aligned with driven pulleys mounted upon opposite ends of a blade support shaft and linked to one another via multiple belts. This alignment evenly balances the load transfer while facilitating the use of vibration isolators between the engine, gear box and frame. A hydraulically controlled depth stop mechanism is included for setting a maximum cut depth. The engine speed is controlled by an electronic governor. A multi-speed transmission is included to afford high and low ranges for the saw. A single control lever is provided to shift between high and low ranges, between forward and reverse directions, and to raise and lower the saw.

This is a divisional of application Ser. No. 08/370,374, filed Jan. 9,1995 now abandoned.

FIELD OF THE INVENTION

The present invention is related to a saw for cutting concrete, stone,asphalt and other similar surfaces, and in particular, to a selfpropelled saw utilizing an in-line engine arrangement with improvedspeed, performance and depth controls.

BACKGROUND OF THE INVENTION

The present invention is described below in connection with the concreteindustry by way of example only but is equally useful in cutting otherhard surfaces.

In the concrete industry, when building bridges, buildings, roads andthe like, it is often necessary to pour large horizontal slabs ofconcrete. Once poured, it is desirable to machine the slab. Suchmachining may include cutting seams completely through the slab (to formexpansion joints and to allow for foundation shifting), cutting notchespartially into the slab (to create stress cracks along which the slabwill split), cutting multiple grooves into the slab to create a highfriction surface such as for bridges, grinding the surface of the slaband the like. Various types of concrete saws may be utilized to carryout these machining tasks. In larger industrial applications, large selfpropelled saws are used which are powered in a variety of manners, suchas by gasoline, diesel, electric, propane, and natural gas enginesmounted on the saw. While performing a cut, the operator walks behindthe saw to control the direction, cutting speed, cutting depth and thelike.

Self propelled concrete saws are mounted upon rear drive wheels and upona hinged front axle assembly which hydraulically raises and lowers thefront end of the saw. The front axle assembly includes a heightadjustment cylinder that is attached to a front axle assembly having thefront wheels thereon. The front axle assembly pivots downward away from,and upward toward, the saw frame when the cylinder extends and retractsthereby raising and lowering the saw. The saw blade is mounted upon ablade support shaft proximate the front of the saw, and thus as thefront end is raised and lowered the cut depth is varied.

When cutting a notch partially into a slab, it is desirable to maintainthe cut at an even and pre-set depth. Also, when cutting extremely deepnotches or cutting through thick concrete, the concrete saw is unable todo so in a single pass. Hence, multiple passes are necessary within asingle groove. Generally, it is desirable to remove an even portion ofthe concrete during each pass.

Self propelled concrete saws have been proposed which utilize a depthstop mechanism attached to the front axle assembly. The depth stopmechanism includes a threaded rod stem extending vertically between thefront axle assembly and the control panel. The upper end of the rod stemincludes a knob and the lower end is threadably secured within a linkageto the front axle assembly. The linkage dictates a depth to which thefront axle assembly may lower the saw. As the operator screws the rodstem in one direction, the linkage is moved outward away from the frameto prevent the front axle assembly from collapsing against the frame,thereby setting the depth of cut.

The conventional mechanical depth stop mechanism has met with limitedsuccess since it requires the operator to turn the rod stem a pluralityof times in either direction to adjust the cut depth. This operation istime consuming and undesirable (generally, the operator must rotate therod stem 13 times to vary the cut depth by two inches). Additionally,the rod stem has proven unreliable and prone to fail since it fatiguesand vibrates during operation until it brakes. Also, quite often the sawis dropped during loading and unloading and when being moved off of theedge of a slab of concrete. Jolting forces upon the front wheels aretransmitted directly to the rod stem and, quite often, bend or break therod stem. When the rod stem bends, it becomes difficult to turn andcreates an unpredictable relation between the number of rod stem turnsand the variation in the cut depth. Further, the rod stem is subjectedto adverse weather conditions and often rusts, which also renders therod stem difficult to turn.

Past concrete saws have further provided an indicator for measuring thedepth of the cut. These systems displayed the approximate depth of thecut relative to a fixed reference point, namely the concrete surface.The depth indicator system includes a lever arm having one end attachedto the front axle assembly and attached to a cable and pulleyconfiguration which drives an indicator dial. The lever arm moves thecable about the pulleys, while the cable is tensioned by a spring. Thepulleys rotate the indicator dial. However, this system has provenunreliable since the spring breaks and the cables slip upon the pulleys.This system further requires a direct path between the dial and thelever arm for the cable which further complicates the system design.

Conventional self propelled concrete saws include a gasoline, diesel,propane, or electric engine aligned along an axis transverse to thelongitudinal axis of the saw frame. This transverse arrangement alignthe engine crankshaft parallel to the rotational axis of the saw blade,to afford an easy design for interconnecting pulleys upon the crankshaftand the saw blade.

However, this transverse engine alignment limits the physical size ofthe engine that can be practically used since the engine length islimited by a maximum acceptable width of the saw to allow the saw topass through door opening (e.g. 36 inches).

Further, the driving engines are typically unbalanced between the frontand the rear ends thereof (also referred to as the fan end and the driveend). Thus, the concrete saw receives an unbalanced engine load acrossits width. Additionally, some types of engines include a heavy drive end(proximate the crankshaft) while other types of engines include a heavyfan end (proximate the fan blade). Each concrete saw must be balancedand thus must be designed to compensate for the unbalanced engine load.Hence, concrete saws utilizing the first type of engine are unable to beused with the second type of engine and vise versa.

During a cutting operation, the concrete saw is supported by the rearwheels and the saw blade in a triangular support pattern. The saw bladeand diagonally opposed rear wheel form a hypotenuse of the trianglesupport pattern. The saw tips across this hypotenuse in a directiondictated by the lateral position of the center of gravity. By way ofexample, when the blade is mounted on the right side of the saw and whenan engine is used having a heavy drive end (proximate the left side),the saw tips across the hypotenuse of the support triangle toward theleft side of the saw (away from the other supporting rear wheel).Divergently, when the blade is mounted on the right side and an engineis utilized having a heavy fan end, the saw tips across the hypotenusetoward the right side of the saw (toward the other supporting rearwheel). When the saw tips across this hypotenuse away from thesupporting rear wheel, it bends the blade, induces side tension thereonand causes blade core cracking, all of which shorten the life of theblade. Thus, it is highly important to design the saw such that itslateral center of gravity is located upon the side of the trianglesupport pattern adjacent the rear wheels. Past systems have addressedthis concern by including a torsion bar support system within the frameor by placing excess weight proximate the base of the triangle supportpattern (i.e., proximate the rear wheel remotely located from thehypotenuse).

However, once the saw is balanced for a particular engine type and for asaw blade mounted on one side thereof, the saw is not easily modified tomount the blade on the opposite side. As noted above, the saw isbalanced to locate the center of gravity on the side of the hypotenuseof the triangle support pattern proximate the saw blade and the rearwheels. Once the saw blade is moved to the opposite side, thismodification chances the triangle support pattern, such that thehypotenuse thereof extends between the new position of the saw blade andthe diagonally opposed rear wheel. However, moving the saw blade doesnot shift the center of gravity. Instead, the hypotenuse of the trianglesupport pattern shifts to the opposite side of the center of gravitysuch that the saw tips across the hypotenuse in a direction away fromthe supporting rear wheel. Hence, when the saw blade is moved to theopposite side of the saw, the saw becomes unbalanced and shortens thelife of the blade due to side tensions, bending, cracking and the like.This unbalanced arrangement also causes the saw to cut crooked, causesthe blade to wear unevenly and renders the saw more difficult to steer.

In addition, the foregoing balancing problem prevent the use ofdifferent types of engines upon the same saw frame. As explained above,switching the engine type similarly moves the center of gravitylaterally across the saw and across the hypotenuse of the trianglesupport pattern. Thus, saws having transversely aligned engines operateoptimally with a single type of engine and with the saw blade mounted ona predefined side. Any variation from this basic design renders the sawunbalanced and shortens the life thereof.

Further, the transverse engine alignment has prevented conventional sawsfrom adequately isolating engine vibration from the saw blade. Enginevibrations, when transmitted to the saw blade, cause the blade tosimilarly vibrate which induces jolting, high intensity impact loadsbetween the blade and the concrete surface. These impact loads cause thediamonds within the blade to break and chip, thereby shortening theblade life. In the past, engines have been mounted upon rubber mountingblocks in an attempt to isolate the engine from the concrete saw frame,and thus from the saw blade.

As noted above, the crankshaft projects from one side of the concretesaw. Pulleys are provided upon the outer end of the crankshaft and uponthe saw blade supporting shaft. Once the belts are tightened, asubstantial bending force is induced upon the drive end of thecrankshaft and upon the end of the blade supporting shaft proximate thepulley. This bending force, in combination with the unbalanced engineweight, necessitates the use of extremely rigid engine mounting blocksproximate the drive end of the engine and the belt and pulley assembly.As the hardness of the mounting blocks increases, the block's ability tosuppress vibrations decreases. Thus, the hard blocks afford littlevibration suppression. Hence, the unbalanced loading of the engineacross the width of the saw prevents the proper type of mounting blocksto be used which would effectively isolating engine vibrations from thesaw blade.

The effectiveness of mounting blocks in this unbalanced environment isfurther reduced by the fact that the belt and pulley assembly induces asubstantial bending force upon the drive end of the crankshaft. Thisbending force creates an unbalanced force upon the mounting blocks,whereby the mounting blocks experience vibrations in a substantiallyshear direction (i.e., across the width of the blocks). Mounting blocksoperate optimally when vibration forces are directed directly into theblock (in a compression direction) and are not designed to suppressvibrations induced in a lateral or shear direction.

The bending effect upon the crankshaft further reduces the life of theengine. Generally, engines are designed with light shell type bearingsto support the crankshaft. These shell type bearings are not designedto, nor capable of, withstanding substantial side loads (i.e., loadingforces in a direction transverse to the rotational axis of thecrankshaft) over a substantial period of time. Hence, conventional sawsrequired the use of engines containing specially designed bearingsintended to withstand such side loads. Alternatively, when engines areutilized with light shell type bearings, an additional bearing assemblymust be added proximate the drive pulleys to afford supplemental supportagainst side loading. These conventional systems have proven undesirablesince they increase the system cost and complexity. Moreover,conventional engines have experienced reduced life since the bearingstherein fail prematurely.

Further, the life of the pulley and belt arrangement is further reducedby the fact that the belts bend the crankshaft and blade support shaftuntil the pulleys run unevenly. This uneven alignment causes the innermost belt to be tighter than the outermost belt, thereby causing unevenwear upon the belts. By unevenly loading the belts, the conventionalbelt and pulley arrangements were less efficient in transferring enginepower to the blade shaft.

As the number of belts increases, the uneven loading therebetweensimilarly increases and thus the conventional belt and pulleyarrangement was limited in the number of belts to be used.

Concrete saws mount the saw blade support shaft within rotary bearingslocated on the bottom of the saw frame. These bearings are subjected toharsh operating conditions since they are constantly subjected toconcrete and water slurry emitted from the cut. Past support bearingshave been unable to seal adequately the bearing from the environment.Past concrete saws have been unable to shelter these support bearingsfrom the slurry concrete composition which wears upon the bearing sealsand causes failures. These bearing systems require daily lubrication topurge contaminants. However, even with daily lubrication, these bearingshave a very limited life. The life of the bearings is further reduced bythe uneven loading created by the belt-pulley arrangement located on oneend of the blade support shaft.

In the past, concrete saws have been proposed which utilize a gear boxproximate the saw blade and along one side of the frame adjacent thetransversely aligned engine. Conventional gear boxes include an outputshaft which directly engages the saw blade. However, these conventionalgear box designs position the gear box immediately adjacent andsurrounding the rotational axis of the saw blade. Thus, the gear box, ifformed too large, interferes with the available cut depth since the gearbox housing contacts the concrete surface if the saw is completelylowered. To avoid such interference, the gear box is maintained small orreplaced with a pulley.

However, as the gear box is reduced in size, it is less capable ofdissipating heat and becomes easily overheated. To reduce thetemperature within the gear box, water cooled gear boxes have beenproposed. Water cooled gear boxes circulate water through a water to oilheat exchanger. However, the oil within the gear box still experiencesextreme temperatures as it passes through the gears. In fact, thelubricant within the gears may flash to a temperature as high as 270° atthe point of contact with the gears, even though the remainder of theoil reservoir is cooled to approximately 180°. When the oil lubricantflashes to this extremely high temperature, it's chemical compositionbreaks down thereby reducing the life of the gear box.

Further, it is often desirable to perform a dry cutting operation inwhich no separate water source is necessary for spraying water onto theblade (water is used during wet cutting to cool the blade and to removethe concrete particles from the cut). Dry cutting is desirable to avoidthe water lines and extra slurry processing equipment utilized in a wetcutting operation. However, the reduced equipment advantage is obviatedwhen a water cooled gear box is utilized since a water reservoir andwater lines must be used with the gear box.

Concrete saw engines also experience overheating since the engine iseither air cooled or when cooled with a radiator that is located alongone side of the saw frame and exposed to adverse operating conditionswhich tend to plug up the radiator.

Past saws also provide the opening to the fuel tank at an intermediatepoint along the tank. Generally, when fuel is added, the saw is in araised position thereby tilting the fuel tank such that the opening isat an intermediate height within the tank. Thus, fuel tended to sloshout once filled. Also, conventional fuel tanks draw fuel from the tank,via an opening in the bottom of the tank, through a fitting and hose.Thus, when the fitting or hose leak, the tank is drained. Utilizing anopening in the bottom of the tank also draws foreign material from thetank with the fuel.

Further, conventional fuel systems utilize a gauge located within thefuel cap of the tank. The gauge included a dial connected to a stemextending into the tank and having a float on its lower end. The stemrotated the fuel gauge depending upon the position of the float.However, a hole was required within the cap between the fuel tank andthe gauge to admit the stem. Fuel tended to splash into the gauge aboutthe stem. In addition, air was allowed into the fuel tank about thestem.

Conventional concrete saws utilize a mechanical governor for controllingthe RPMS (revolutions per minute) of the engine and the saw blade. Everytype of saw blade operates at a different optimal rotational speed. Theoptimal speed for a given blade is achieved by adjusting the governor todirect the engine to rotate at a corresponding speed. Mechanicalgovernors are generally controlled by some form of biasing force, suchas afforded by a spring, to control the governor. The biasing force isadjusted to adjust the engine's operating speed. Hence, the biasingforce controlling the governor is changed each time the type of blade ischanged to one with a differing optimal rotational speed. These changeswere cumbersome and time consuming.

Further, mechanical governors are easily tampered with by operatorsduring use since the mechanical governor is readily accessible to theoperator. Normally, the governor is set to operate the engine at anoptimal RPM level for a given blade type and size. While manufacturersor distributors set the governor to achieve the optimal RPM level,operators often adjust the governor setting to increase the engine'soperating speed (and thus the blade speed). However, these operatoradjustments can exceed the optimal RPM level for the particular blade,thereby "over speeding the blade" and shortening the blade life.Overspeeding the blade also places the saw in an unsafe operatingcondition. The risk of overspeeding a blade is further complicated bythe fact that most concrete saws are designed to operate with aplurality of blade sizes and thus are capable of rotating at extremelyhigh speeds. Operator tampering with the governor can also cause theengine to run at an unsafe RPM level.

To convert between different blade sizes, the engine speed must beadjusted, along with the belt and pulley ratio between the engine andthe saw blade. In the past, the necessary adjustments were quitedifficult and required multiple saw components to be changed. Further,previous belt and pulley arrangements afforded little speed reductionbetween the saw blade speed and the engine RPM level. Thus, the engineRPM level was set at the optimal RPM level of the saw blade. Generally,the blade's optimal RPM level is below the engine's optimal RPM level(i.e., the RPM level at which the engine generates a maximumhorsepower). Thus, the engine rotates slower than its optimal RPM leveland at a reduced horsepower.

Conventional concrete saws were unable to operate at an optimal enginespeed since the pulley arrangement offered little or no gear reductionbetween the saw blade and the engine. The driven pulley is provided uponthe saw blade support shaft proximate the saw blade. As the saw bladepulley increases in diameter, it interferes with, and reduces, theavailable cut depth. To maximize the available cut depth, small pulleysare provided upon the blade shaft, thereby limiting gear reductionbetween the engine and the blade.

Conventional saws are difficult to re-configured to reverse therotational direction of the saw blade. The blade's rotational directionis reversed between downward cuts (i.e., with normal concrete cutting ornotching operations) and upward cuts (i.e., to clean out a cut or notchand to perform grooving and grinding operations). Cuts are cleaned toremove any excess cutting material before adding a silicon or rubberbased material, such as a elastometer, to form an expansion joint (i.e.allow for expansion and contraction due to weather changes). Groovingand grinding operations use an upward cut since the saw utilizes a stackof saw blades arranged side by side. These blades have a tendency, whenrotated in a downward direction, to drag or pull the saw forward fasterthan desired. To prevent such dragging, the blades are rotated in anupward direction, thereby creating a rearward force pushing the sawbackward. Self propelled concrete saws include driving wheels that pushgroovers or grinders forward at a desired rate.

Further, conventional saws having a transverse alignment are limited inthe amount of power transferable between the engine crankshaft and theblade support shaft. As noted above, saws are limited in width in orderto pass through standard doors. Conventional saws attach the drivepulleys to the crankshaft and thus the drive pulleys extend beyond thedrive end of the engine. The number of pulleys are limited by the widthof the saw. The number of pulleys and belts dictate the amount of powerwhich is transferable between the crankshaft and the saw blade. Thenumber of pulleys useful with the engine is limited by the saw width,and thus the power transferable to the saw blade is similarly limited.

Further, conventional saws utilize a drive mechanism for moving the sawwhich affords a single gear ratio. The drive mechanism utilizes avariable speed hydrostatic pump and motor which is adjustable inrotational speed and rotational direction. The hydrostat is attached,via gears and a chain to the drive wheels. This conventional drivemechanism afforded the operator a single operating range dependent uponthe gear combination between the drive wheel and the motor.

Often, it is desirable to drive the saw at a low ground speed, such aswhen effecting deep cuts, wherein the ground speed is adjustable inextremely small increments. At other times, it is desirable to drive thesaw at a high ground speed, such as when effecting shallow cuts ormoving between cuts.

The conventional drive mechanism afforded a single operating range forthe ground speed. Pence, when the operator desired to change between lowand high ground speeds, the operator must change the gears or sprocketsupon one or both of the drive motor and drive wheels. By changing thesesprockets, the operator was able to change the gear ratio and thus theground speed range. This mechanical change was time consuming andundesirable.

In addition, the conventional drive mechanism maintained an engagedrelation between the drive wheels and the drive motor at all times. Thedrive motor rotated in forward and reverse directions and afforded alocked or stopped position. Thus, the saw was unmovable by the operatorwhen the engine was turned off.

Moreover, the conventional saw utilized multiple control leversincluding separate levers to raise and lower the saw, move the sawforward and backward, and to drive and stop the saw. These controllevers were difficult to use.

Finally, conventional saw offered little operator comfort since the sawwas extremely noisy and transferred substantial vibrations to theoperator through the control levers and handle bars. Conventional sawswere particularly noisy since the transversely aligned engine directedthe air and noise from the engine to one side which effectivelysurrounded the operator.

A need remains within the industry for an improved concrete saw. It isan object of the present invention to meet this need and to overcome thedisadvantages experienced heretofore.

SUMMARY OF THE INVENTION

According to the present invention, a concrete saw is providedcharacterized by an engine mounted with its longitudinal axis extendingparallel and in-line with the longitudinal axis of the concrete saw.This in-line configuration is arranged such that the crankshaft extendssubstantially along the central axis of the saw frame and parallel tothe direction of the cut. The present in-line arrangement enables theuse of larger engines, such as water cooled engines, since the length ofthe engine is not limited by the saw's width. Larger engines translateinto more productive cutting, longer saw life, lower maintenance, lessengine noise, lower emissions and greater fuel efficiency.

The engine speed is controlled by an electronic governor which maintainsthe engine speed at one of a plurality of desired constant speedsdictated by a speed selector switch set by the operator. These speedsmay include an idle speed, a maneuvering speed, and multiplepredetermined operating speeds. The electronic governor with theselector switch maintains a constant engine speed for any load up to amaximum load thereby providing a constant RPM speed (to maximize power,fuel efficiency and blade usage efficiency). The electronic governorfurther prevents tampering with the governor setting thereby eliminatingoverspeeding of the blade for greater safety.

The drive end of the crankshaft receive a drive assembly (which mayinclude a clutch) and a right angle gear box directly thereon. The gearbox is located remote from the saw blade and provides a double endeddrive shaft extending from both ends thereof across a width of the saw.Both ends of the gear box shaft receive gear box pulleys equally loadedwith an even number of belts that are attached to corresponding pulleyson opposite ends of the saw blade supporting shaft.

The present right angle gear box arrangement splits the drive loadequally between both sides of the saw, thereby preventing inducedbending loads on the crankshaft and thus extending the engine life, thebearing life, and the belt life. Equally, loading the belts also allowsmore pulleys and belts to be used to transfer the driving force from theengine to the saw blade since the inner and outer belts are evenlytensioned. These additional belts and pulleys maximize the transfer ofengine power to the blade and increase cutting power. In addition, evenbelt tensioning affords longer belt life, engine life and bearing life,and consistent power output. The present gear box arrangement furtherprovides the ability to reverse the rotational direction of the bladefrom a downward cut to an upward cut by simply rotating the gear box180°.

The present gear box is located remote from the cutting environment andthus the gear box size does not interfere with the available cut depth.Hence, the present gear box is sufficiently large that it need not bewater cooled. The gear box further provides for any desired amount ofspeed reduction thereby allowing the engine and the saw blade to rotateat different optimal speeds. By balancing the load in the foregoingmanner, the in-line configuration allows the saw to cut equally wellwith blades mounted on either side thereof.

Opposite ends of the gear box output shaft include stainless steeltapered sections for receiving the pulleys. These tapered sectionsafford quick and easy pulley removal.

The gear box is mounted upon, and separated from the engine frame, viaisolators. Opposite ends of the gear box are evenly loaded, and thus thevibration forces from the engine are directed directly into theisolators. Hence, these forces are effectively eliminated. By evenlydistributing the load onto the isolators into direct compression lessrigid isolators may be utilized which in turn more effectively suppressengine vibrations.

The present gear box and isolator arrangement prevents the transfer ofvibrations to the frame and the saw blade which measurably lengthens theblade life, decreases component fatigue, reduces engine noise andprovides greater operator comfort.

The operator's comfort is further enhanced by utilizing a soft moldedhandle for the control levers and by providing soft molded handle gripson the handle bars.

The saw blade support shaft is mounted, at opposite ends, to the framethrough heavy duty bearings. A shield extends between the inner sides ofthe bearings to protect same from the environment. The outer sides ofthe bearings are located immediately adjacent pulleys which protect thebearings from dirt and concrete slurry. The pulleys evenly load thebearings. The bearing arrangement provides multiple seals between thebearings and the environment to lengthen the bearing life.

The present concrete saw includes a two-speed transmission with aneutral position attached to the rear drive wheels. The transmission isdriven by a hydraulic motor which is supplied oil flow via a variablesteed, reversible hydrostatic pump. A single control lever controls thetwo steed transmission and the hydrostatic pump's volummetric flow rateand direction of fluid flow. This heavy duty transmission arrangementprovides longer transmission life and allows the operator to easilyswitch between high and low ranges (such as when cutting deep andshallow cuts) without changing the drive sprocket. The neutral positionallows the operator to move the saw with the engine OFF. A neutralsafety start switch is also provided which prevents the engine frombeing started unless the transmission is in neutral. A parking brake isprovided to prevent the saw from moving if the transmission is left inneutral. Optionally, an indicator light is included to notify theoperator when the transmission is in neutral.

A single control lever is provided whereby the hydrostatic pump isshifted from forward-to-stop-to-reverse as the control lever is movedbetween forward, middle and backward positions. The lever further shiftsthe transmission between high, neutral and low ranges when moved fromside to side. Finally, the lever includes a momentary rocker switchthereon which raises and lowers the saw.

The present concrete saw includes a front axle assembly which ispivotally mounted at its rearward end to the saw frame. The forward oropposite end receives wheels to carry the front end of the concrete saw.The front axle assembly includes first and second cylinders attachedthereto proximate its frame mounting pivot point. The first cylinder iscontrolled to rotate the axle assembly about its pivot point to raiseand lower the saw. The second cylinder represents a hydraulic adjustabledepth stop mechanism which prevents the front end of the saw blade frombeing lowered below a maximum cut depth. This hydraulic depth stopcylinder is controlled via a set/reset switch upon the saw controlpanel. The set/reset switch opens a normally closed valve which allowsan amount of hydraulic fluid to be delivered to and captured within thedepth stop cylinder. During operation, the operator opens the valve andadjusts the saw height, via the lifting cylinder, to a desired height.Once this valve is closed, the depth stop cylinder will allow the saw tobe raised, but not lowered below the set depth.

The inventive saw further uses an electronic depth indicator whichidentifies the cut depth relative to a variable or resetable referencepoint. The depth indicator is attached to a potentiometer connected tothe front axle assembly. The potentiometer changes its resistive readingas the front axle assembly rotates. The depth indicator measures thisresistance and indicates a corresponding depth. Once the user sets thedepth stop mechanism at its desired depth, the user similarly resets thedepth indicator by "zeroing" the sensor (via a second potentiometer)when the blade touches the cutting surface.

The depth indicator may be tied to the transmission or hydrostatic pumpto slow the saw speed when the cut depth begins to decrease. Often, whenthe saw begins to move to fast, the depth of the cut decreases. Thedepth indicator senses this depth variation and slows the transmission.Once the saw's speed is reduced sufficiently, the saw blade returns tothe desired cut depth.

The present concrete saw is further characterized by a mid-mountedradiator on the fan end of the engine remote from the cutting area. Acrankshaft mounted fan allows a low straight through air flow whichreduces the overall saw height. The fan is aligned to draw air from theback end of the saw toward the engine and blow hot air away from theoperator. This arrangement further centers the weight of the radiatorupon the frame and draws clean cool air through the radiator. Theradiator includes wide fin spacing to pass dust easily. The fan isprovided with nylon reinforced blades which minimize the effects ofvibrations from the engine transferred through the crankshaft. Thisnylon blade allows a crankshaft mounted fan whereas past systems mountedthe fan on the water pump to avoid such vibration. A foam mat isprovided over the in-take side of the radiator to collect dust andparticulate material drawn therethrough. The foam mat is provided with ahydrolyt activant therein which collects water from the air to retainmore effectively particulate material. The mat is simply removed andeasily cleaned, thereby removing the need to wash the fins within theradiator, such as with a high pressure washer thereby reducing the riskof bending the radiator fins. This separate filtering mat enhances theradiators life and effectiveness. In addition, an engine shroud orcowling is provided about the engine to enclose same. The engine shroudor cowling reduces engine noise and includes vents through itsforwardmost face. The fan directs hot air forward through the vents inthe front end of the engine cowling away from the operator, therebyreducing noise.

Optionally, a shroud may be provided along the bottom of the framemaking a line transverse thereto and located at a point there along toprevent air circulation from the front of the saw back under the saw andup through the radiator.

A single hydraulic reservoir is used for the lifting assembly and thehydrostatic unit for lower maintenance and greater reliability. Areplaceable spin-on filter is provided to collect particulate materialwithin the hydraulic fluid.

The present concrete saw further includes a top mounted fuel pickupsystem, reducing the likelihood of the fuel draining from the tank ifthe hose breaks. The fill cap to the fuel tank is located at theforwardmost and highest point upon the fuel tank to prevent fuelspillage and leakage when the saw is raised. The fuel tank is contouredwith a ramped bottom side to maximize air flow and capacity to theradiator.

An engine cowling is included to reduce engine noise and protect theengine from the environment.

Electronic engine gauges are included for greater reliability, lessleakage and lower maintenance. An isolated handle bar system is providedwith paddled handles to reduce vibrations for greater operator comfort.Replaceable locking collars are used to provide adjustable handle bars.A circuit breaker panel is provided for protecting the electricalcomponents from overloading. A battery acid drip tray is included aboutthe battery to protect the frame and the paint from corrosion. Sidecable battery mounts are provided for greater safety and better cableconnections.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention noted above are explained inmore detail with reference to the drawings, in which like referencenumerals denote like elements, and in which:

FIG. 1 illustrates a side elevational view of a concrete saw accordingto the present invention while in a lowered position;

FIG. 2 illustrates a side elevational view of a lower portion of theconcrete saw of FIG. 1 while in a raised position;

FIG. 3 illustrates a front elevational view of the concrete saw of FIG.1;

FIG. 4 illustrates a side view of the forward end of the present sawwith of portion thereof broken away to illustrate the drive assembly;

FIG. 5 illustrates a top sectional view of a right angle gear box of aconcrete saw according to the present invention;

FIG. 6 illustrates a side sectional view of an isolator and mountingbracket for supporting the right angle gear box taken along line 6--6 inFIG. 3;

FIG. 7 illustrates a top plan view of the front axle assembly with thelifting and depth stop assembly, along with a top sectional view of thetransmission, taken along line 7--7 in FIG. 1;

FIG. 8 illustrates a schematic diagram of the hydraulic system utilizedto control the lifting and depth stop assembly of FIG. 7;

FIG. 9 illustrates a side sectional view of an electronic clutchassembly which may be used in an alternative embodiment of the presentinvention;

FIG. 10 illustrates a perspective view of the control panel with a sideplate removed therefrom to expose a handle bar assembly;

FIG. 11 illustrates a side sectional view of the upper rear portion ofthe present saw showing the fuel tank;

FIG. 12 illustrates a schematic view of the control system forcontrolling the electronic governor, the depth indicator and theautomatic depth control mechanism;

FIG. 13 illustrates a side elevational view of the control assemblyconnecting the control lever with the hydrostatic pump;

FIG. 14 illustrates an end elevational view, as viewed from the rear ofthe saw, of the control assembly connecting the control lever with thetransmission;

FIG. 15 illustrates a side elevational view of one embodiment of thecontrol lever with a blade height control switch; and

FIG. 16 illustrates an exploded view of an alternative embodiment of thecontrol lever with a blade height control switch.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 generally illustrates a concrete saw according to the presentinvention having an engine 2 mounted to and extending along thelongitudinal axis of a saw frame 4. The drive end of the crankshaftdriveably receives a drive plate assembly 20 mounted directly theretoand upon a drive end of the engine 2. A gear assembly 6 is mounted onthe outer end of the drive plate assembly 20. The gear assembly 6provides a right angle power coupling for driving a saw blade, theoutline of which is generally shown in dashed lines. A fan end of theengine 2 driveably receives a fan blade directly mounted on the oppositeend 10 of the crankshaft. The fan blade (not shown) is positionedproximate the radiator 12 for cooling the engine 2. A multi-sizedtransmission 14 is mounted on the rear end of the frame 4 in drivingengagement with the drive wheels 474 via a chain 470. The transmission14 is driven by a hydraulic motor 18 (FIG. 7) which is powered by ahydrostatic pump 15 (FIG. 7). A depth control assembly 16 is mountedupon the lower side of the frame 4 to control the depth of a cuteffected by the saw blade. A control handle 7 and control handle linkage9 control the hydrostatic pump 15 (FIG. 7), transmission 14 and depthcontrol assembly 16. The remaining sections and subsections of theinventive saw will be described in more detail below in connection withthe corresponding drawings.

Turning to FIG. 4, the gear assembly 6 and the drive plate assembly 20securely mounted to the drive end of the engine 2 are described in moredetail. The drive plate assembly 20 includes a flywheel housing 42securely mounted to the face of the engine along one side and securelyreceiving a gear box plate 44, via bolts 45 along the opposite outerface. The gear box plate 44 is securely bolted to the gear box housing46 via bolts 47. A crankshaft 8 is provided including a flange 22,mounted on it's outer end, which rotates with the crankshaft 8 duringoperation. The flange 22 extends into the flywheel housing 42. Aflywheel 24 is bolted to the flange 22 at points 25. The flywheel 24serves to balance the engine when in operation. The flywheel 24 includesa flat base 26 having a lip 27 extending from a backside thereof, tosecurely receive the flange 22. The base 26 includes an outer rim 28formed with a stair-stepped cross-section. The flywheel 24 affords thenecessary inertial weight to balance rotation of the engine. The rim 28includes a ledge 30 at an intermediate step there about to receive adrive plate 32 securely bolted thereto. The ledge 30 includes an outerface 33 extending outward therefrom to fit snugly against the driveplate 32.

The drive plate 32 is mounted to the flywheel 24 via bolts 34. The driveplate 32 includes a hole through the center thereof which receives adrive plate splined coupling 36 partially extending therethrough. Thecoupling 36 includes a flange 37 about it's periphery having holestherethrough to receive rivets 5 which secure the flange 37 to the driveplate 32. The coupling 36 includes a plurality of splines about it'sinner periphery and extending transverse thereto. The splines slidablyreceive a splined shaft 40 from the gear box 6. The splined connectionprovides a direct driving connection between the gear assembly 6 and theflywheel 24. This splined connection affords linear motion between thegear assembly 6 and the engine 2 to prevent the transfer of linearloading directly along the rotational axis of the splined shaft 40.

A pilot bearing 48 is received within a recess in the front of theflywheel 24. The pilot bearing 48 receives a smooth forwardmost end ofthe splined shaft 40 to centrally locate the splined shaft within theflywheel 24 and carries any side load of the splined shaft 40. The gearbox plate 44 mounts the gear box 6 to the engine.

Turning to FIG. 5, the internal workings of the gear assembly 6 areexplained in detail in connection therewith. The gear assembly 6includes a gear box housing 60 having openings through opposite sidesand the face thereof. The gear box housing 60 securely receives taperedsupport extensions 72 on opposite sides thereof. The splined shaft 40includes a forward or outer end 41 which is received within a spiralbeveled pinion gear 50. Support bearings 52 and 54 are located about theouter end 41 of the splined shaft 40 and upon opposite sides of thepinion gear 50. The pinion gear 50 driveably engages a second spiralbeveled gear 56 arranged at a right angle to the pinion gear 50. Thesecond gear 56 is fixably mounted upon a driven shaft 58 which extendsthrough the sides of the gear box 60 and through the support extensions72. The spiral beveled pinion gears 50 and 56 afford a right angletransfer of the engine's rotational force between the splined shaft 40and the driven shaft 58. The spiral beveled design enables a right angletransfer of a large driving force at high speed while minimizing noise.

The driven shaft 58 extends outward in both directions from oppositesides of the gear box housing 60 and includes tapered sections 62 and 64on opposite ends thereof. The driven shaft 58 is formed of a corrosionresistant high tensile strength material, such as stainless steel. Thedriven shaft 58 is rotatably mounted within bearings 66-69 seated withinjournaled recesses along the support extensions 72. The tapered ends 62and 64 afford easy removal and installation of gear box pulleys 70 and71. When removing gear box pulleys 70 and 71, the user merely need "pop"the pulleys 70 and 71 loose from the tapered ends 62 and 64 of the shaft58. Thereafter, the pulleys 70 and 71 easily fall off of the drivenshaft 58. The sides of the gear box housing 60 are mounted with bolts 78to the support extensions 72 and the force of the housing 60 mounted toa rear face to the gear box plate 44 with the bolts 47.

The gear box enables an amount of gear reduction to be achieved betweenthe motor speed and the rotary speed of the driven shaft 58 by adjustingthe diameters of the pinion gears 56 and 52. By providing optional gearreduction, the gear box is able to maintain the engine at its optimalRPM level i.e., such as 3000-3500 RPM while allowing the saw blade torotate at an optional blade speed.

The gear assembly 6 affords a mechanism for easily reversing therotational direction of the saw blade. To do so the gear box plate 44(FIG. 4) is simply detached and rotated by 180 degrees. In particular,to reverse the rotational direction of the saw blade, the gear box plate44 is released from the flywheel housing 42 by removing the bolts 45.The belts are also removed. As the gear box plate 44 is removed, thesplined shaft 40 slidably disengages the coupling 36. The gear boxhousing 60 is rotated 180 degrees about the rotational axis of thesplined shaft 40 to reverse the direction of rotation of the drivenshaft 58. The gear box plate 44 is remounted such that the splined shaft40 is again engaged within the coupling 36. The bolts 45 are reinserted.

By rotating the gear box in this manner, an operator is able to convertbetween a down cutting operation and an up cutting operation.

Turning to FIG. 3, the support extensions 72 include upper and lowersupporting flanges 100 and 102, respectively, located at opposite endsthereof. The upper and lower support flanges 100 and 102 are locateddiametrically opposite one another at respective ends of the housing.The support flanges 100 and 102 include threaded recesses for receivingmounting bolts 104. While the upper and lower support flanges 100 and102 mirror one another, only the support flanges directed downward areutilized at any given time. The upper support flanges 100 are providedfor use when the gear box 60 is rotated 180 degrees about the rotationalaxis of the spline shaft 40 (FIG. 4). Upper and lower isolators 110 and112 are provided to effectively isolate vibrations within the engine andthe gear box from the frame 4. The gear assembly 6 is mounted, via theisolators 110 and 112, upon a rear engine support 114 having cuter arms116 extending in opposite directions and legs 118 directed downward.

As illustrated in more detail in FIG. 6, the arm 116 of the enginesupport 114 is sandwiched between the upper and lower isolators 110 and112. The upper isolator 110 is further compressed between the arm 116and the lower support flange 102. The upper isolator 110 includes anintegral isolator collar 120. The isolator collar 120 include a holetherethrough to receive a sleeve 126 about the bolt 124. Optionally, thelower isolator 112 may be formed with the collar or both isolators 110and 112 may include concentrically formed isolators. Similar variationsmay be utilized so long as the isolators 110 and 112 provide a completeand continuous barrier of flexible resilient material between the arm116 and the bolt 124 and the supporting flange 102. The bolt 124 isreceived within the tubular sleeve 126 which extends through the holesin the upper and lower isolators 110 and 112. The sleeve 126 extendsfrom the flange 102 to the flat washer 128. A lock washer 130 isprovided proximate the head of the bolt 124 to resist loosening thereof.The isolators 110 and 112 are made of a flexible resilient material toabsorb vibrations induced thereon by the engine support 114 and the gearbox 60. In this manner, the isolators 110 and 112 prevent the transferof vibrational forces between the flanges 102 and the arms 116. Thesleeve 126 provides a rigid core whereby the bolt 124 is tightenedagainst the flat washer 128 at one end and against the flange 102 at theopposite end. Isolators are also used at the fan end of the enginebetween the engine and the frame.

Returning to FIG. 3, the engine support 114 is bolted to the frame 4,via L-shaped brackets 130 and bolts 132 and 134. As illustrated in FIG.4, the legs 118 include holes therethrough aligned along a verticalaxis. The L-shaped brackets 130 include elongated slots 136 which alignwith the holes to afford a passageway to receive the supporting bolts132. The engine support 114 further includes forwardly projecting ledges138 on opposite sides thereof. The ledges 138 have threaded holes 140therethrough. The holes 140 threadably receive bolts 142. The bolts 142may have heads on the upper or lower ends so long as the bolts 142firmly abut against the upper surface of the frame 4. The bolts 142, bythreadably engaging the ledges 138, function to tighten the belts and assafety stops to prevent the engine support 114 from being lowered belowa minimum desired height. To adjust the tension in the belts 144 and146, the bolts 132 (FIG. 3) are loosened to allow linear movementbetween the legs 118 and the vertical portion of the L-shaped brackets130. The vertical support bolts 142 are turned to span the distancebetween the ledges 138 and the upper surface 143 of the frame 4. Oncethe heads of the bolts 142 engage the frame 4, they lift the enginesupport 114. Moving the engine support 114 in this manner moves thepulleys 70 and 71 similarly and along a vertical path to tighten andloosen the belts 144 and 146. Once the belts 144 and 146 aresufficiently tightened, the holding bolts 132 are tightened to preventfurther movement between the engine support 114 and the frame 4.

A balanced tension force is maintained upon opposite sides of the gearbox 60 by evenly adjusting the bolts 142, thereby evenly loading thegear box pulleys 70 and 71. By maintaining this balanced force, the loadis directed evenly downward along opposite sides of the gear box 60 in adirection parallel to the longitudinal axis of the belts 144 and 146.This loading force is evenly applied to the isolators 110 and 112,thereby applying compression loads directly along the longitudinal axes148 and 150 (FIG. 3) of the isolators 110 and 112 and minimizing theshear forces applied thereto. Thus, the isolators 110 and 112 need notbe designed of a material sufficiently rigid to withstand excess shearforces. Isolators afford an increased vibration dampening characteristicas the rigidity thereof is decreased. By using even loading thedampening ability of the isolator system is enhanced.

With reference to FIGS. 1 and 7, the frame 4 is constructed from a pairof longitudinally extending channel members 152 secured at opposite endsand at intermediate points to transverse support brackets 156. Top sidesof the longitudinal members 152 and 154 and the support brackets 156receive a flat mounting shell 158. The front corners of the shell 158(FIG. 1) includes recesses 160 extending along opposite sides of thechannel members 152. The recesses 160 provide an operating region forthe belts 144 and 146, and the saw blade pulleys 172 and 174.

Turning to FIG. 3, the lower sides of the forward most ends of thechannel members 152 securely receive blade shaft mounting bearings 166.The mounting bearings 166 include flat upper surfaces with threadedholes that abut against the channel members 152. Bolts 134 extendthrough the brackets 130 and channel members 152 and are fixedly boltedto the bearings 166. Each bearing 166 includes a housing about sealedbearings 181. Inner seals 183 are surrounded with grease 185. Inner andouter caps 165 and 167 are mounted to the housing via bolts. The innerand outer caps 165 and 167 are rotatably joined, via flexible seals 168with a saw blade drive shaft 175. The blade shaft 175 is constructed ofstainless steel material and includes outer portions extending beyondopposite ends of the outer caps 167. The outer most portions of theblade shaft 175 extend beyond the bearings 166 and include key grooves170 extending longitudinally along the outer surface thereof. The outersections of the blade shaft 175 receive driven pulleys 172 and 174. Thepulleys 172 and 174 are maintained upon the blade shaft 168 via taperedlocking hubs 187. The inner caps 165 are enclosed within opposite endsof a flexible shield 178 and secured thereto, such as with a hose clamp(not shown). The shield 178 prevents exposure of the inner sealed endsof the bearings to contaminates produced during a cut. The shield 178further prevents a user's clothing from being wrapped around the bladeshaft 168. The shield 178 is formed of semi-resilient material tomaintain its form when in use.

The outer seals within the outer seal flanges 167 are partiallyprotected from environment contaminants by the pulleys 172 and 174 eventhough a slight air gap is formed therebetween. The pulleys 172 and 174create a "slinging effect" during operation which tends to prevent thecontaminates from collecting proximate the seals within the outer caps167. Thus, the pulleys 172 and 174 and shield 178 protect and lengthenthe life of the bearing seals.

Turning to FIG. 9, an alternative embodiment for the drive plateassembly 20 is illustrated wherein an electronic clutch is utilized. Theelectronic clutch 220 includes a housing 42 which is securely mounted tothe end of the engine with the crankshaft 8 extending into and throughan opening in the front face thereof. The crankshaft 8 includes a flange222 on its outer end which is bolted to a backside of the flywheel 224within a circular lip 227. In this alternative embodiment, the flywheel224 is constructed somewhat different in that it includes a flat outeror front face having a slightly raised circular ridge 229 locatedconcentrically thereabout proximate a center portion of the flywheel224. The circular ridge 229 receives flat springs 231 extending radiallyoutward there from and mounted via bolts 233. The outer ends of thesprings 231 are mounted securely to an armature disk 235 forming a ringhaving an inner circumference concentrically extending about the outercircumference of the circular ridges 229. The armature disk 235 includesan armature engaging face 237 directed away from the flywheel 224 andaligned immediately adjacent a corresponding rotor engaging face 239upon a rotor disk 241. Rivet recesses 254 are provided within thearmature disk 235 for securing the springs 231 to the disk 235. Whendisengaged, an air gap 243 is provided between the engaging faces 237and 239.

The armature disk 235 is mounted to the flywheel 224 via the springs 231to maintain a fixed rotary position therebetween. However, the flatsprings 231 allow a longitudinal movement between the flywheel 224 andthe steel armature disk 235 in a direction parallel to the rotationalaxis of the flywheel. This longitudinal movement allows the armaturedisk 235 to close an air gap 243 when the armature and rotor engagingfaces 237 and 239 are magnetically drawn against one another. The flatsprings 231 normally bias the armature disk 235 away from the rotor disk241 to maintain the air gap 243 between the engaging faces 237, 239while disposed in these remote positions, the armature and rotor disks235, 241 are allowed to rotate relative to one another.

The rotor disk 241 is securely mounted upon a drive plate coupling 236extending along the core and through the center of the rotor disk 241.The coupling 236 is securely mounted upon a gear box input shaft 240 viaa nut 242. Optionally, a splined shaft and coupling may be used as inFIG. 4 or a straight shaft with a key way and the like. An outerjournaled end portion 218 of the input shaft 240 is securely receivedwithin a pilot bearing 248 which rotatably centers the input shaft 240relative to the flywheel 224. The pilot bearing 248 is received within ajournaled recess proximate the center of the flywheel 224.

The rotor disk 241 includes concentric raised inner and outer rings 245and 247 located on the back side thereof and spaced a distance apart.The inner and outer rings 245 and 247 receive a field coil 249 having arectangular cross-section therebetween. The rings 245 and 247 maintainan extremely close tolerance with the field coil 249. The field coil 249is securely mounted upon the gear plate box 244 with a mounting ring 217interposed therebetween. A hole through the gear box plate 244 admits apower cable 252 to supply current to the field coil 249. The power cable252 is connected with a battery and with a switch located upon thecontrol panel of the saw. The switch affords the user the ability toturn the field coil 249 on and off when turned between first and secondpositions. Optionally, the switch may engage a braking mechanism oncethe clutch is disengaged when turned to a third position.

As the user selectively applies power to the field coil, the electronicclutch assembly 220 is engaged and disengaged.

In particular, when no current is applied to the field coil 249, thearmature disk 235 is biased, via the flat springs 231 to a positionproximate the flywheel 224 (as shown in FIG. 9) and remote from therotor disk 241. When in this normally biased position, an air gap 243 isprovided between the armature and rotor disks 235, 241. At this time,the flywheel 224, which is driven by the crankshaft 8, rotates freelywithout driving the gear box input shaft 240. The user engages the sawblade by turning on the control switch, thereby energizing the fieldcoil 249. Once energized, the field coil 249 induces a magnetic fieldthrough the rotor disk 241 which draws the steel armature disk 235against the rotor disk 241. Once these faces are frictionally engaged,the rotor disk 241 is driveably rotated by the armature disk 235,thereby similarly driving the input shaft 240 and the saw blade.

While the embodiment of FIG. 9 illustrates an input shaft 240 which issecurely mounted to the coupling 236 via a nut 242, the electronicclutch assembly 220 may similarly be implemented utilizing the splinedconfiguration illustrated in FIG. 3.

Optionally, a blade brake may be provided in combination with theelectronic clutch to afford means to halt rotation of the saw blade oncethe clutch is disengaged. The blade brake may be included within theelectronic clutch housing 242, within the gear box housing 60 or alongthe blade shaft 168.

For instance, as shown in FIG. 9, the electronic brake may be providedabout the outer periphery of the rotor disk 241 by including anextension rim 270 about the rotor disk 241 and integrally formedtherewith. The extension rim 270 includes an inner lip 272 whichsecurely receives a second flat spring 274. The spring 274 is attachedto the lip 272 via bolts 276. The outer ends of the spring 274 aresecured, via rivets 278, to a second armature disk 280. The gear boxplate 244 includes a raised outer rim 282 forming a second rotor disk.The raised outer rim 282 and the armature disk 280 include engagingfaces 284 and 286 which frictionally engage one another to resistfurther rotation of the rotor disk 241. The raised rim 282 includes ahollowed recess 284 therein which receives a second field coil 287having control cables 288. The control cables 288 are attached to thesame switch used to control the electronic clutch. When the user turnsthe switch to a position which disengages the field coil 249 and engagesthe field coil 286, the field coil 249 releases the armature disk 235while the field coil 286 attracts the armature disk 280. Thus, the rotordisk 241 disengages the armature disk 235 while the armature disk 280engages the outer rim 282. In this manner, a brake is implemented.

Alternatively, a disk brake assembly may be provided along the gear boxdriven shaft 58 or along the blade shaft 168. As illustrated in FIG. 5,the disk brake assembly 800 may be located proximate the outer end ofthe driven shaft 58. The disk brake assembly 800 includes a disk brake802 securely mounted upon the driven shaft 58 and located proximate thetapered end 62 thereof. The disk 802 extends about the driven shaft 58between the pulley 70 and the outer end of the support extension 72. Abrake housing 804 is located upon the outer end of the gear box plate 44and includes a recessed chamber 806 therein, along with a slot 808 toreceive the disk 802. The recessed chamber 806 includes inner and outerbrake pads 810 and 812 located immediately adjacent and upon oppositesides of the disk 802. The brake pads are movably mounted to the housing804 via pad actuators 814. The actuators 814 may comprise electronicactuators powered by a 12 volt remote source and connected to a brakeswitch located upon the control panel.

The actuators 814 may be constructed to extend when energized by theswitch upon the control panel. When so energized, the actuators drivethe brake pads 810 and 812 against opposite sides of the disk 802 toestablish a frictional engagement therebetween. The switch controllingthe disk brake may be included within a three way switch, wherein theswitch engages the electronic clutch when in a first position,disengages the electronic clutch within a second position and engagesthe disk brake when in a third position.

Optionally, disk brakes may be provided upon both ends of the drivenshaft 58.

As a further alternative, the brake assembly may include mechanicalsprings to normally bias brake pads into a frictionally engagingrelation with the driven shaft 58 or blade shaft 168. When so engaged,the brake pads would prevent rotation of the engaged shaft. The brakeassembly would further include a disengaging actuator, such as anelectric, magnetic, pneumatic or hydraulic actuator to physicallycontract the mechanical springs and disengage the brake pad from thecorresponding shaft. For instance, if an electronic actuator isutilized, when the user turns the control switch to engage theelectronic clutch, the electronic disengaging brake actuator wouldforcibly disengage the brake pads from the corresponding shaft. Theelectronic actuator would maintain the brake pads in this disengagedposition until the user turned the control switch to release theelectronic clutch. When the clutch is released, the electronic actuatorsimilarly releases the disk brake, thereby allowing the mechanicalspring to automatically bias the brake pad against the driven shaft 58or blade shaft 168. This in turn automatically halts rotation of the sawblade. Alternatively, the blade brake assembly may be controlled from aseparate switch provided to the user.

In addition, the electronic clutch assembly is controlled such that theoperator is only able to engage the clutch when the speed selectorswitch is set at one of the slower engine speeds (i.e., an idle speed ora maneuver speed). This assembly prevents the operator from engaging theclutch when the engine is running at the higher cutting speeds, therebyrendering a safer system. This safety feature may be implemented in avariety of ways. For instance, the clutch engaging switch may beconnected in series with a flywheel rotational speed detector. Theflywheel detector will only enter a closed circuit state, therebyconnecting the electronic clutch switch with the electronic clutch, whenthe flywheel is rotating below a maximum safety threshold (i.e., belowan engine cutting speed). Alternatively, the electronic clutch may beconnected to the micro-controller 950 (FIG. 12) and controlled thereby,such that the electronic clutch switch only energizes the field coilwithin the electronic clutch when the micro-controller 950 determinesthat the speed selection switch 606 is in one of the lower speedsettings (i.e., in the idle speed setting or the maneuver speedsetting). As a further option, a series of relays may be installedbetween the electronic clutch switch and the field coil of theelectronic clutch. These relays may be attached to the leads 953 and 951to provide a close circuit between the electronic clutch switch and theelectronic clutch when the leads 951 and 953 indicate that the speedselection switch 606 is set in one of the first and second positions(i.e., in an idle position or a maneuver position).

Turning to FIGS. 1, 2 and 7, the lifting and depth stop mechanism isexplained in more detail. The lifting and depth stop mechanism 16includes a front axle assembly 302 formed as a rectangular shapedchannel having front and rear pivot pins 304 and 306 extending fromopposite sides thereof and positioned proximate front and rear endsthereof. The front pivot pins 304 rotatably support wheels 308 whichsupport the forward end of the concrete saw. The rear pivot pins 306 arerotatably mounted within bearings 310 securely bolted to the lower sideof the frame 4. The bearings 310 are located at an intermediate pointalong the frame 4 to position the wheels 308 forward of the center ofgravity of the concrete saw.

The front axle assembly 302 further includes push brackets 312-314mounted between the rear pivot pins 306 and extending radially outwardfrom the rotational axis defined by the rear pins 306. The push brackets312-314 are arranged to extend upward at an obtuse angle to the planeformed by the surface of the front axle assembly 302. The push brackets312-314 are pivotally mounted via rod 315 to lifting rams 316 and 318 ofcylinders 320 and 322, respectively. The hydraulic cylinders 320 and 322include rearward ends mounted to the frame 4 via a pivot pin 324. Thehydraulic cylinders 320 and 322 are powered by a hydraulic pump remotelylocated therefrom.

The hydraulic cylinder 320 operates to lift the saw. The hydrauliccylinder 322 functions as a depth stop mechanism to set a maximum depthof a cut by the saw blade. When the hydraulic cylinder 320 extends, theram 316 drives the push brackets 312-314 forward, thereby causing thefront axle assembly 302 to rotate about the pivotal axis formed alongthe rear pivot pins 306. As the front axle assembly 302 rotates aboutthe rear pivot pins 306, the wheels 308 are driven downward, therebylifting the front end of the concrete saw (FIG. 2). Divergently, whenthe cylinder 320 is contracted, the front axle assembly 302 rotates inan opposite direction to lower the front end of the concrete saw (FIG.1). The depth stop cylinder 322 is controllably set to capture a setamount of fluid, thereby defining a predefined maximum cut depth.

Turning to FIG. 8, a schematic of the hydraulic system utilized tocontrol the lifting and stop assemblies is described hereafter. An oilreservoir is generally illustrated at point 400 which supplies hydraulicfluid to a hydraulic pump 405 via a filter or strainer 302. The pump 405is driven by a DC motor 404 which is controlled by an electronic rockerswitch located upon the control lever 7 (FIG. 1). This switch includesan energizing plate generally designated by the reference numeral 532.The pump 405 outputs fluid to a node 408 which communicates with acontrol valve 410. The control valve 410 may be set at any desired levelsuch as approximately 2600 psi, wherein it opens when the pressure atnode 408 exceeds the preset level. When the fluid pressure exceeds thevalve 410 preset level, the hydraulic fluid is returned to the reservoir400 via the return line 412. From node 408, the hydraulic fluid isdelivered to a check valve 414 which operates as a one way valve todeliver hydraulic fluid to its discharge side and not allow reversedirection hydraulic fluid flow.

Fluid from the check valve 414 flows through node 416 from whichseparate hydraulic lines 418 and 420 deliver fluid to the liftingcylinder 320 and the depth stop cylinder 322, respectively. The node 416further connects with a second strainer or filter 422 which in turnconnects with a normally closed solenoid control valve 424 and a flowcontrol safety 426. The flow control safety 426 dictates a maximum flowrate wherein fluid may be returned, via line 428 to the reservoir 400.

The control valve 424 is normally closed until energized by a contactplate 530 within the rocker switch 514 on the control lever. Whenenergized, it allows oil to flow along the return line 428. Duringoperation, when the operator rotates the rocker switch to a liftingposition, the switch 514 energizes the contact 532 and activates themotor 404 to drive the pump 405, thereby delivering hydraulic fluid tothe lifting cylinder 320 via supply line 418. When the operator desiresto lower the saw, the rocker switch 514 is toggled in an oppositedirection (i.e. to a lowering state) whereat a contact plate 530 isenergized and the normally closed control valve 424 is opened. Whenopen, the control valve 424 allows hydraulic fluid to be discharged fromthe cylinder 320 and returned to the reservoir 400. A second flow ratecontrol valve 430 is provided within the hydraulic line 418 to set themaximum flow rate with which hydraulic fluid is discharged from thelifting cylinder 320. The flow rate control valve 430 is variablyadjusted by the operator to change the flow rate, thereby changing therate at which the saw is lowered. The safety flow rate control valve 426dictates a maximum rate at which the cylinder 320 may be collapsed,thereby setting the maximum lowering rate.

Returning to node 416, a second normally closed solenoid control valve432 is provided within hydraulic line 420 to control the flow of fluidto the depth stop cylinder 322. The second normally closed solenoidcontrol valve 432 is controlled via a depth stop set/reset switch 604located upon the control panel.

As illustrated in FIG. 10, the depth stop control switch 604 includes aset state 608 and a reset state 610. When in the set state, the controlswitch 604 maintains the solenoid control valve 432 in a non-energizedstate (i.e., in a closed state). Thus, when in the set position, thecontrol switch 604 prevents the flow of fluid to the depth stop cylinder322. Divergently, when the control switch 604 is set in the resetposition, it energizes the control valve 432 thereby allowing the flowof fluid along line 420 to and from the depth stop cylinder 322.

During operation, when a user desires to adjust the height of the sawand set the depth stop mechanism at a new height, the operator turns thedepth stop control switch 604 to its reset position, thereby energizingthe control valve 432 and allowing fluid to flow to and from thecylinder 322. Next, the operator uses the rocker switch 514 upon thecontrol handle to raise and lower the saw, via the cylinder 320. Once adesired height is reached, the operator toggles the control switch 604to the set position, thereby closing the valve 432 and capturing apredefined amount of fluid within the cylinder 322. When in this state,the ram within the cylinder 322 may extend, however, it may not retractbeyond a length dictated by the amount of fluid captured therein. Bycapturing fluid in the cylinder 322, the valve 432 sets the maximumdepth of cut.

Returning to FIG. 7, the transmission 14 is driven by a hydraulic motor18 that receives fluid from a hydrostatic pump 15 via hydraulic linesconnected between ports 17.

In the preferred embodiment, the motor 18 rotatably drives a two-speedtransmission 14 at a variable rate in forward and reverse directions.The drive direction and speed of the motor 18 are determined by thefluid flow rate and direction from the pump 15. The pump 15 represents avariable displacement pump, the volummetric displacement of which variesas a swash plate control lever upon the pump 15 is moved. The fluid flowdirection from the pump 15 is also controlled by the swash plate.

A control cable 11 is connected, at one end, to the swash plate toadjust the position thereof, and thus control the fluid flow rate anddirection. The opposite end of the control cable 11 is connected to thelever 7. A linkage rod 13 connects the transmission 14 and the controllever 7. As explained below in more detail, movement of the controllever 7 along a first path (e.g., forward and backward) causes movementof the control cable 11, thereby changing the fluid flow rate anddirection of the pump 15. Thus, backward and forward movement of thecontrol lever 7 varies the rotational speed and direction of the motor18 and the saw's ground speed. As explained below, movement of thecontrol lever 7 along a second path (e.g., side to side) causes movementof the linkage rod 13, thereby shifting the transmission between high,neutral and low gear ratios. Thus, by moving the lever 7 side to side,the operator is able to change the range of ground speeds.

FIG. 7 illustrates the transmission 14 in more detail. The transmission14 is driven by the hydraulic motor 18 via a splined output shaft 450which is driveably received within a splined recess in a pinion gear452. The motor 18 is securely mounted to the transmission housing 454.The pinion gear 452 is constructed in a tubular shape with a splinedinterior and a gear toothed exterior and received within the housing454. The transmission 14 further includes a cluster gear assembly 456and an output gear assembly 458. The output gear assembly includes largeand small gears 460 and 462 separated by a spacer 461 and securelymounted on an output shaft 464 which is rotatably supported withinbearings (not shown). The bearings are supported within journaledrecesses in the transmission housing 454. The output shaft 464 extendsthrough a hole in the transmission housing to receive a drive gear 468(FIG. 1) on the outside thereof. The drive gear 468 engages a chain 470(FIG. 1) which is securely received about a wheel gear 472 locatedproximate the drive wheels 474 at the rear end of the frame.

The cluster gear assembly 456 (FIG. 7) includes large and small gears476 and 478 securely mounted immediately adjacent to one another in anabutting relationship. The cluster gear assembly 456 is rotatablyreceived upon a cluster gear shaft 480 such that the cluster gearassembly 456 is rotatable about the cluster gear shaft 480 and slidablealong the rotational axis thereof. The cluster gear assembly 456 furtherincludes a flared end member 482 proximate one end thereof to form agroove 483 which receives a half moon shaped end 484 located on theouter end of a shifting fork 486. The shifting fork 486 is constructedin an L shape with the shifting end 484 on one end thereof and with ahousing 487 on the opposite end thereof for secure engagement with ajournaled outer end of a shifting shaft 488.

The shifting shaft 488 is securely mounted, via an intermediate togglearm 489, to the lower end of the linkage rod 13 that is slidablycontrolled by the lever 9. When the user moves the lever 9 in atransverse direction, the linkage rod 13 is slid along its longitudinalaxis thereby pivoting the toggle arm 489 about its center pivot point.As the arm 489 pivots, it drives the shifting shaft 488 along it'slongitudinal axis. As the shaft 488 slides in this manner, it similarlymoves, via the shifting fork 486, the cluster gear 456 along it'srotational axis and along the cluster shaft 480. As the cluster gear 456slides along it's rotational axis, it shifts between low and highranges. While in a low range, the smaller cluster gear 478 is positionedto driveably engage the larger output gear 460. While in the high range,the cluster gear is positioned such that the larger cluster gear 476driveably engages the smaller output gear 462. The larger cluster gear476 maintains driving engagement with the pinion gear 452 throughoutoperation regardless of it axial position along the cluster shaft 480.

The transmission 14 also includes a neutral position at which thecluster gear assembly 456 and the output gear assembly 458 aredisengaged from one another. The shifting fork 486 shifts the clustergear assembly 456 to a neutral state when the gears 476 and 478 arelocated between and, disengaged from, the gears 462 and 460.

The transmission 14 further includes a neutral safety switch 490 whichsenses the position of the shifting fork 486 and delivers acorresponding electronic signal to the starting switch. This signalindicates when the cluster gear assembly 456 is engaged with the outputgear assembly 458. The neutral safety switch 490 creates an open circuitstate within the electrical loop between the starter switch and thestarter when the gears are engaged. This open circuit state prevents thestarter from being actuated while the transmission 14 is in gear. Theneutral safety switch 490 creates a closed circuit state between thestarter and starter switch when the transmission 14 is in a neutralstate.

The transmission 14 affords the user greater flexibility with respect tothe speed at which the concrete saw is to be moved. For instance, whenthe operator is performing a deep cut, or a grooving or grindingoperation, the transmission 14 may be placed in it's low range, whilethe pump 15 affords fine tuning adjustment of the saw's speed. Once theoperator completes a cut and desires to move the saw to the next cut,the operator may shift the transmission 14 into it's high range whilemaintaining control of the saw's speed via the hydrostatic pump 15.

Optionally, the transmission 14 may be implemented using a single speedtransmission with a neutral and safety start switch. When a single speedtransmission with a neutral is utilized, the control handleconfiguration is simplified to allow for linear movement of the controlhandle along a single direction. As the control lever 7 is moved alongthe single direction, the control cable 11 connected thereto controlsthe hydrostatic pump 15 as explained above. A transmission may furtherbe included which offers more than two speeds, such as a three or fourspeed transmission, provided that transmission includes a neutral and asafety start switch. When a multi-speed transmission is utilized, thecontrol panel configuration simply need be modified to allow for side toside movement of the control lever 7 along a path sufficient to shiftbetween these gears.

It is to be understood that if a multi-speed transmission is utilized(such as a five speed transmission), the control handle assembly may bemodified to provide for shifting of the gears between such positions.

FIG. 15 illustrates a side sectional view of the control lever 7 whichcontains an electronic height control switch (also referred to as arocker switch) generally designated by the reference numeral 500. Thecontrol lever 7 includes a stem 502 with an upper end securely mountedwithin the base 504 of the handle grip 506. The handle grim 506 includesa recessed chamber 508 therein which communicates with the front face510 of the handle grip 506 via an opening 512. The chamber 508 andopening 512 partially receive a rocker switch 514 which projects throughthe opening 512 and beyond the face 510. The rocker switch 514 ismounted upon a pivot pin 516 which is secured, at opposite ends, to thehandle grip 506. The rocker switch 514 includes a substantially circularcross-section with a V-shaped notch 518 cut in the outwardmost sectionthereof. The rocker switch 514 is hingeably mounted to a contact supportplate 520 at point 522 located radially outward from its central pivotpin 516. The contact support plate 520 is formed in a substantiallyrectangular cross-section with the contact connecting point 522proximate the center of its forwardmost side. The contact support plate520 is pivotally mounted to the handle grip 506 at point 524 proximatethe center of its rearward side.

The contact support plate 520 and the rocker switch 514 are biased to anintermediate position (as illustrated in FIG. 15) wherein the pivotpoints 516 and 524 and the connection point 522 are aligned along acommon central axis. The contact support plate 520 includes upper andlower contacts 526 and 528 mounted thereon and extending along the upperand lower sides thereof.

The handle grip 506 further houses receiving contacts 530 and 532aligned in an abutting relationship with the contact support plate 520and positioned immediately above and below the corresponding upper andlower contacts 526 and 528.

The contact support plate 520 is positioned such that the upper contactregion 526 electronically engages the receiving contact 530 when thesupport plate 520 is rotated upward about the pivot point 524.Similarly, the support plate 520 is located such that the lower contactarea 528 electronically engages the lower receiving contact 532 when thesupport plate 520 is pivoted downward about the pivot point 524.

During operation, the rocker switch 514 may be pivoted about its centralpin 516 in the upward direction (as illustrated by the clockwise arrow534) or downward (as illustrated by the counterclockwise arrow 536).When rotated in the clockwise direction, the rocker switch 514 causesthe contact support plate 520 to rotate downward about pin 524 until thelower contact area 528 engages the receiving contact 532. Similarly,when rotated downward, the rocker switch 514 drives the support plate520 upward until the upper contact 526 engages the receiving contact530.

Returning to FIG. 8, when the rocker switch 514 is rotated clockwise(i.e., upward), the contacts 528 and 532 are engaged thereby energizingthe motor 404 and directing the pump 405 to supply fluid to the liftingcylinder 320. In this manner, the cylinder 320 is electronicallycontrolled to lift the concrete saw by driving the rocker switch 514upward. To effect a lowering operation, the rocker switch 514 is rotateddownward (i.e., counterclockwise) such that the contacts 526 and 530engage one another. As illustrated in FIG. 8, when the contact 530 isenergized it opens the normally closed control valve 424 therebyallowing fluid to be discharged from the cylinder 320 along lines 418and 428 to the reservoir 400. In this manner, the hydraulic cylinder 320is electronically controlled to lower the saw.

As a further alternative, the rocker switch may be implemented asillustrated in FIG. 16. FIG. 16 illustrates control lever 7 having arocker switch 1000 included therein with three leads 1002 extendingthrough a hollow channel within the control lever. The switch 1000includes a rocker grip 1004 within its outer face which is normallybiased to a neutral middle position. The rocker 1004 may be toggledupward or downward to close a circuit within leads 1002 which controlsan electric motor and control valve (FIG. 8) to raise and lower the saw.The switch 1000 may be one which is offered by Otto Controls of OttoEngineering Inc. from Carpentersville, Ill.

Turning to FIG. 10, a portion of the control panel is illustratedcontaining the depth indicator 600, a depth indicator zero/reset dial602, the depth stop set/reset switch 604 and the engine speed selectorswitch 606. The depth indicator 600 includes an analog dial indicatingthe current depth of the cut being effected by the saw blade withrespect to a predefined reference level. This reference level may bereset at any time during operation to the current setting of the sawblade by rotating the depth indicator zero control 602. When utilizingthe depth stop mechanism to set the maximum depth of a cut, the depthstop set/reset switch 604 is utilized. The set/reset switch 604 includesa two state switch. When in the set state 608 (as illustrated in FIG.10), the control valve 432 (FIG. 8) is closed, thereby capturing acurrent amount of fluid in the depth stop cylinder 322. When it isdesirable to reset the depth control cylinder 322 to a different level,the set/reset switch 604 is toggled to the reset state 610, therebyenergizing the normally closed control valve 432 and allowing fluid toflow therethrough along line 420 (FIG. 8). This reset state 610 ismaintained until the height control cylinder 320 is adjusted via therocker switch 514 to a desired height. Thereafter, the set/reset switch604 is toggled to the set state 608 and the valve 432 is closed tocapture a current amount of fluid within the depth stop cylinder 322.When so captured, this fluid prevents the cylinder 322 from retractingbeyond its current position, thereby preventing the front axle assemblyfrom lowering beyond this level. It should be understood that the depthstop cylinder 322 will be extended, while the control valve 432 isclosed, as it will simply form a vacuum within the fluid chamber.

Turning to FIGS. 13-14, the control assembly for the control lever 7 isillustrated, generally designated by the reference numeral 700. Thecontrol assembly 700 includes an upper face plate 708 having a H-shapedpattern 710 cut therethrough which defines the control path of the lever7. The control lever 7 may move within the control pattern 710 along aforward-reverse direction (as defined by arrow 712) and along aside-to-side direction (as outlined by arrow 714).

The control lever 7 includes a lower end pivotally mounted at anintermediate point along a transverse support bracket 702. The supportbracket is mounted upon a pivot pin 704 secured at opposite ends to theassembly housing 706. The pivot pin 704 has a longitudinal axisextending parallel to the direction of movement 712. The support bracket702 allows the lever 7 to be moved from side-to-side along arrow 714 asthe bracket 702 rotates about the pin 704.

The control lever 7 is further mounted along its side to a brace 716having a lower end pivotally mounted at point 718 to an upper flange 720of the support bracket 702. The brace 716 provides support for thecontrol lever 7. The brace 716 and the control lever 7 sandwich ahalf-moon shaped guide plate 722 therebetween which is securely mountedupon the flange 720 and extending upward therefrom in abutting relationwith the control lever 7. A teardrop shaped link 724 is mounted upon anopposite side of the brace 716 at the point 718. The teardrop shapedlink 724 extends outward from the pivot point 718 to pivotally receivethe control cable 11 at its outermost point 728. The teardrop 724 isfixedly mounted along an outer side of the brace 716, to maintain afixed angular relation therebetween at all times. This fixed arrangementcauses the link 724 to pivot around 718, thereby driving the cable 11forward and backward along arrow 730 as the brace 716 is pivoted aboutthe point 718. This pivotal motion is caused by the handle 7 when theoperator moves the handle along either side of the H-shaped pattern 710in a direction parallel to the arrow 712.

The support bracket 702 includes a lower extension 754 that istriangularly shaped and extends downward below the pivot pin 704. Theextension 754 includes flared bottom end 756 which securely receives thesheath for the control cable 11. The extension 754 includes a ball jointconnector 758 upon one side thereof. The ball joint 758 pivotallyadjoins one end of a linking arm 760. An opposite end of the linking arm760 is pivotally connected with the toggle arm 489. The arm 489 pivotsabout its center point 762 upon a brace 764. The lower end of the arm489 pivotally joints the shifting shaft 488.

As the lever 7 is moved along the path 714, the lower extension 754pulls and pushes upon the linking arm 760 which pivots the toggle arm489. The toggle arm 489 directs linear motion within the shaft 488,thereby shifting the transmission between high, neutral and low states.

For purposes of explanation, it is assumed that regions 740 correspondto the forward movement of the concrete saw while regions 742 correspondto reverse movement of the concrete saw. Regions 744 correspond to stoppositions while region 746 corresponds to a neutral position.

During operation, when a user desires to move the concrete saw forward,the control lever 7 is moved to one of regions 740. When so moved, thelink 716 rotates forward, thereby causing the link 724 to rotatedownward and push upon the cable 11. Responsive thereto, the cable 11directs the hydrostatic pump 15 to pump fluid in a direction necessaryto rotate the motor in a direction corresponding to forward movement ofthe saw. As the lever 7 is moved further forward from the stop position744 toward the forwardmost position 740, the volummetric displacement ofthe pump 15 increases thereby increasing the forward rotational speed ofthe motor 18 from a stopped position to a fastest rotational speed.

Similarly, when the operator desires to move the concrete saw in areverse direction, the control lever 7 is moved to one of the points742. As the lever 7 is moved in this direction, the brace 716 rotatestherewith, causing the link 724 to pull the cable 11. As the cable 11 ispulled, it directs the hydrostatic pump 15 to pump fluid in a directionto rotate the motor 18 in a direction corresponding to reverse movementof the concrete saw. As the lever 7 is moved from the stop positions 744to one of the reversemost positions 742, the cable 11 directs thehydrostatic pump to increase its flow rate, thereby increasing themotor's reverse rotational speed. In this manner, the operator may movethe concrete saw forward and backward or maintain it in a haltedposition by moving the lever 7 from one of points 742 to one of points740 or 744.

The control lever 7 similarly effects shifting of the transmission 14between high, neutral and low ranges by moving laterally in thedirection of arrow 714. By way of example, the region 748 may correspondto a low range while the region 750 may correspond to a high range. Whenthe user desires to operate in the low range, the lever 7 is shiftedlaterally to the low range area 748, thereby causing the support bracket702 to pivot in a clockwise direction (as viewed in FIG. 14), whichcauses the extension 754 to push the link 760 downward, thereby rotatingthe toggle arm 489 counter clockwise (in FIG. 14) and driving the shaft488 inward toward the transmission 14. Thus, the shaft 488 causes thelow range gears to engage.

Divergently, when the user desires to operate in a high range, the lever7 is moved laterally along direction 714 to region 750. This lateralmovement causes the support bracket 702 to rotate in the oppositedirection thereby causing the extension to rotate in the oppositedirection and pull the arm 760 upward. Upward movement of the arm 760rotates the toggle arm 489 clockwise (FIG. 14), thereby pulling outwardupon the shaft 488 and shifting the gears to a high range.

If the lever 7 is maintained at the neutral state 746, the linking arm760, toggle arm 489 and shaft 488 shift the gears into a neutral state.

FIG. 10 illustrates the control panel 850 which contains a raised rearface 852 and front and back walls 854 and 856, respectively. The frontand rear walls include holes 855 and 857 therethrough that alien withone another. Aligned hole pairs are located on opposite sides of thefront and rear walls 854 and 856. While only one side of the controlpanel is illustrated, the opposite side includes a similar handleassembly. Each hole pair receives a hollow handle tube 858 which issupportably housed within resilient isolators 860. The isolators may beconstructed of rubber or any similarly resilient material. The isolatorsare fractionally received within U-shaped channel retainers 862 whichhave flared outer sides. The flares outer sides of the retainers 862 arefixedly mounted to side panels for the control panel 850 (the side panelhas been removed for illustration purposes).

Once the retainers 862 are securely affixed to the side panels, theretainers 862 bind the isolators 860 in position which similarly bindthe handle tube 858 against linear movement. The isolators 860 arelocated in abutting relation to the holes 855 and 857 to seal same andthus preventing dirt from entering the control panel and noise fromescaping.

The rear end of each handle tube 858 receives a locking collar 864thereabout. A set screw secures the collar 864 to the tube 858. Thehandle tube 858 slidably a handle bar 866 in a rear end thereof. Thehandle bar 866 includes a resilient handle grip 868 upon its rear endfor the operator to grasp and steer the saw. A locking pin 870 isthreadably received within the collar 864 and passes through a hole inthe tube 858. The lower end of the pin 870 engages the handle bar 866 tomaintain same in a fixed position within the handle tube 858.

The handle assembly of FIG. 10 affords the user with adjustable steeringhandles that are isolated from saw and engine vibrations.

The raised rear face 852 of the control panel includes a top surface 872located above the control panel and the rear face 852. The top surface872 includes a hole 874 therethrough which admits a fuel tank fill spout876 sealed with a fuel cap 878.

FIG. 11 illustrates the fuel tank placement and arrangement in detail. Afuel tank 900 is located immediately below the control panel 850 andspans the distance between the front and rear walls 854 and 856. Thefuel tank 900 is mounted in place via a front support bracket 902 andbolts 904. The fuel tank 900 is formed with a trapezoidal shaped with aramp shaped lower side 906 and with a bottom well 908. The forwardmostend of the tank 900 includes a fill nipple 910 which is sealablyreceived within a lower end of a flexible hose 912. An upper end of thehose 912 is securely received within the fill spout 876 which issecurely mounted to the top surface 872 of the control panel 850. Thefill spout 876 ensures that the fuel filling point remains located abovethe fuel level at all times regardless of whether saw is raised orlowered. The rear end of the fuel tank receives a fuel draw tube 914which includes an open bottom end 916 which draws fuel from the bottomof the tank. The tube 914 is supported by and attached to a fitting 917which also connects with a fuel line (not shown) that delivers fuel tothe engine.

The fuel tank 900 fuel includes a float 918 attached to a stem 920 thatis support ed by an electronic fuel level monitor 922. The monitor 922delivers an electronic signal, via an electric wire (not shown) to anelectronic fuel gauge located on the control panel 850. The outer topsurface 924 of the fuel tank includes a trough along its lengthextending between the front and back ends of the fuel tank. The troughprovides a passage for the fuel line and electric line.

FIG. 12 illustrates the control circuitry for the electronic governor,the depth indicator and the automatic depth controller.

The electronic governor system includes a microcontroller 950, the fourspeed control switch 606, a rotary actuator 952 and the carburetor 954.The control switch 606 is connected to the controller 950 via first andsecond lines 951 and 953, each of which delivers a high or a low signal(e.g., 0 V or 12 V) to identify the current position of the switch 606.For instance, when the switch is set to the first speed (1), both lines951 and 953 output a low signal. When the switch is set to the secondspeed (2), the a first control line 951 outputs a high signal and thesecond line 953 outputs a low signal. When the switch is set to thethird speed (3), the second line 953 outputs a high signal while thefirst line 951 outputs a low signal. When the switch is set to thefourth speed (4) , both lines 951 and 953 output high signals.

The controller 950 receives these high and low signals and identifiesthe desired speed setting. Once the controller 950 receives a speedselection signal, it outputs a control signal along line 957 to theactuator 952 directing the actuator 952 to adjust the setting of thecarburetor 954. For instance, the actuator 952 may be adjusted in alinear relation to the level of the signal from the controller 950 toeffect the desired amount of variation within the setting of thecarburetor. The controller 950 internally stores a separate actuatorcontrol signal for each input signal combination on lines 951 and 953from the selector switch 606, and outputs the corresponding actuatorcontrol signal based on the incoming selector switch signal.

The controller 950 includes a communications port to enable thecontroller to be reprogrammed periodically to adjust the actuatorpositions associated with each speed selector switch position. Thus, thegovernor may be reprogrammed as desired by the manufacturer ordistributor. However, the controller is only adjustable through thissoftware communications link, thereby preventing the operator fromadjusting the carburetor.

FIG. 12 further illustrates the depth indicator system which includesthe depth indicator 600, depth reset knob 602 and depth sensor 958. Thedepth sensor 958 may be a potentiometer (i.e., a variable resister)located upon the front axle assembly proximate the one of the pivot pins306. The depth sensor 958 is located such that the resistance of thepotentiometer varies as the front axle assembly rotates. This resistancevariation maintains a relationship with the rotary position of the frontaxle assembly. The depth indicator 600 includes an ohmmeter whichmonitors the resistance variation across the sensor 958. As thisresistance varies, the dial within the indicator 600 similarly moves toidentify the depth of the cut.

The depth reset knob 602 may also represent a potentiometer connected inseries with the indicator 600 and the sensor 958. The reset knob 602 maybe varied by the operator to adjust the resistance monitored by theindicator 600. In operation, once the user adjusts the level of the sawto a desired reference level (i.e., ground level or the flush with thebottom of a previous cut), the user turns the reset knob 602 until theindicator 600 is "Zeroed". As the knob 602 turns it varies theresistance monitored by the indicator 600 until it displays a zeroreading.

For instance, the indicator 600 may display a maximum cut depth when itreads 0 ohms of resistance and a minimum cut depth when it reads 1000ohms of resistance. The sensor 958 may be configured to vary between1000 and 0 ohms resistance as the front axle assembly rotates between azero cut depth and a maximum cut depth (displayable upon the indicator600). The resistance within the depth reset button may be varied between0 and 1000 ohms.

Assume an operator desired to effect a second pass through a 3 inch deepcut and to remove an additional 3 inches of concrete during the secondpass. First, the operator lowers the blade into the previous 3 inch cut.At this time the sensor outputs a resistance reading corresponding to a3 inch cut (e.g., 700 ohms) and the depth reset knob 602 outputs aminimum resistance (e.g., 0 ohms). The indicator 600 reads 700 ohmswhich corresponds to a 3 inch cut depth. To zero the indicator 600, theoperator turns the knob 602, thereby increasing the resistance outputtherefrom to 1000 ohms. Now the indicator reads 1000 ohms of resistance(i.e., 700 from the sensor and 300 from the knob) and displays a zerocut depth. Thereafter, as the saw blade lowers the sensor 958 decreasesits resistance output thereby decreasing the resistance monitored by theindicator 600 which identifies the new cut depth.

Optionally the depth indicator circuit may be implemented using amicro-controller and any other equivalent electronic circuitry.

FIG. 12 further illustrates a micro-controller 960 which effects anautomatic depth control function. The controller 960 includes aconverter 970 connected to the input leads 961 and 963 which areconnected in parallel with the sensor 958. The converter 970 monitorsthe resistance across leads 961 and 963 and outputs a signalrepresentative of this resistance. The controller 960 reads theconverter output signal to determine if the depth of cut is varying. Thecontroller 960 is activated via a signal from a control switch upon thecontrol panel. The controller 960 delivers an output signal to controlan actuator attached to the control cable 11 to vary the volummetricdisplacement of the pump 15 and thus varying the saw ground speedaccording to the depth of cut.

When the operator desires to activate the automatic depth controlfunction, the operator first sets the saw blade to the desired depth.Thereafter, the operator flips the automatic depth switch whichenergizes the controller 960. Once energized, the controller 960 readsthe current signal from the converter 970 representative of the currentresistance value across the sensor 958. The controller 960 stores thissignal as its reference signal and thereafter continuously monitors thesignal from the converter 970. When the saw ground speed exceeds themaximum speed at which the saw blade is able to maintain a currentdepth, the saw blade begins to lift to a lesser cut depth. The frontaxle assembly similarly moves, thereby adjusting the resistance acrossthe sensor 958. This change in resistance is sensed by the converter 970which outputs a correspondingly different output voltage to thecontroller 960. The controller 960 reads the converter signal,determines that it does not equal the reference signal and calculates adifference between the new converter signal and the reference convertersignal. The controller 960 thereafter outputs a signal to the actuatordirecting the actuator to adjust the control cable 11, thereby reducingthe volumetric displacement of the pump 15 and slowing the saws groundspeed.

The controller 960 continuously monitors the converter output andoutputs a corresponding actuator control signal until the converteroutput signal equals the converter reference signal. In this manner, thecontroller 960 is able to slow the saw ground speed when the saw bladeraises above the desired cut depth. The controller 960 increases the sawaround speed as soon as the saw blade lowers to its desired depth.

From the foregoing it will be seen that this invention is one welladapted to attain all ends and objects hereinabove set forth togetherwith the other advantages which are obvious and which are inherent tothe structure.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. For instance, the depth stop and depth indicatorfeatures may be utilized on any type of saw for cutting hard surfaces.This depth stop feature is not solely for use with saws having anin-line engine arrangement. Additionally, the electronic clutch andbraking features may be utilized on any type of saw regardless ofwhether the saw includes an in-line engine arrangement or the inventivedepth stop feature. Further the inventive drive assembly including thetransmission with a neutral and a hydrostatic pump may be used with anytype of saw regardless of the engine alignment, regardless of the depthstop mechanism and regardless of whether the saw includes an electronicclutch. Similarly, the inventive electronic governor assembly with amultiple speed selection switch may be used on any type of saw, as maythe gas tank, shrouding, and every other inventive feature. Theversatility of the inventive features is contemplated by and is recitedwithin the scope of the claims.

Further, it is to be understood that the control panel will includeadditional control indicators, such as an electronic fuel gauge, atachometer, an oil pressure gauge, a water temperature gauge, an ampmeter, and the like. In addition the panel may include the automaticdepth control switch 987.

Since many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative, and not in a limiting sense.

What is claimed is:
 1. A self-propelled concrete saw comprising:anengine and a saw blade driveably mounted thereto, said saw bladeeffecting a cut within said concrete to a desired cut depth; a body forsupportably housing said engine and saw blade; front and rear wheels forsupporting said body; and a lifting and depth stop assembly, securelymounted between said front wheels and said body, including a firstcylinder to raise and lower a front end of said body and a secondcylinder to set a minimum height to which said body is lowered, saidminimum height corresponding to said desired cut depth, said lifting anddepth stop assembly further including a front axle assembly having aforward end that rotatably receives said front wheels and having arearward end pivotally hinged to said body, and said first and secondcylinders being mounted to said front axle assembly proximate saidrearward end to rotate said front axle assembly about said rearwardpivot point to raise and lower the saw blade, wherein at least one ofsaid cylinders is controllably set to contract to a predefined level,thereby preventing lowering of said saw blade below said desired cutdepth.
 2. A concrete saw according to claim 1, said depth stop assemblyfurther including a pump for driving said first and second cylinders viafirst and second supply lines, first and second valve means locatedwithin corresponding ones of said first and second supply lines tointerrupt the flow of fluid between said cylinders and said pump, andcontrol means for closing said second valve means to trap a desiredamount of liquid within said second cylinder, thereby preventing saidsecond cylinder from contracting beyond a predefined level, whileallowing said second cylinder to expand as directed by said firstcylinder.
 3. A concrete saw according to claim 1, wherein said depthstop assembly further includes an electronic switch, mounted upon acontrol panel of said saw, for setting and resetting said minimum heightto which said second cylinder will contract, thereby setting andresetting said desired cut depth.
 4. A self-propelled concrete sawcomprising:an engine and a saw blade driveably mounted thereto, said sawblade effecting a cut within said concrete to a desired cut depth; abody for supportably housing said engine and saw blade; front and rearwheels for supporting said body; a lifting and depth stop assembly,securely mounted between said front wheels and said body, including afirst cylinder to raise and lower a front end of said body and a secondcylinder to set a minimum height to which said body is lowered, saidminimum height corresponding to said desired cut depth, and a depth stopindicator for identifying a current depth to which said saw blade islowered, with respect to a predefined reference level, said depth stopindicator including means for resetting said reference level to anydesired depth.
 5. A self-propelled concrete saw comprising:a frame;front and rear wheels connected to said frame to movably support theframe on the surface to be cut; a saw blade mounted on said frame forcutting concrete to a preselected cut depth; an engine mounted on saidframe and operatively connected to said saw blade; and a lifting anddepth stop assembly, securely mounted between said front wheels and saidframe, including a first cylinder to raise and lower a front portion ofsaid frame on which said saw blade is mounted and a second cylinder toset a minimum height to which said front portion of said frame islowered, said minimum height corresponding to said desired cut depth,said lifting and depth stop assembly further including a front axleassembly having a forward end that rotatably receives said front wheelsand having a rearward end pivotally hinged to said frame, and said firstand second cylinders being mounted to said front axle assembly proximatesaid rearward end to rotate said front axle assembly about said rearwardpivot point to raise and lower the portion of said frame carrying saidsaw blade, wherein at least one of said cylinders is controllably set tocontract to a predefined level, thereby preventing lowering of saidframe portion and saw blade below said desired cut depth.
 6. A concretesaw according to claim 5, said depth stop assembly further including apump for driving said first and second cylinders via first and secondsupply lines, first and second valve means located within correspondingones of said first and second supply lines to interrupt the flow offluid between said cylinders and said pump, and control means forclosing said second valve means to trap a desired amount of liquidwithin said second cylinder, thereby preventing said second cylinderfrom contracting beyond a predefined level, while allowing said secondcylinder to expand as directed by said first cylinder.
 7. A concrete sawaccording to claim 5, wherein said depth stop assembly further includesan electronic switch, mounted upon a control panel of said saw, forsetting and resetting said minimum height to which said second cylinderwill contract, thereby setting and resetting said desired cut depth. 8.A self-propelled concrete saw comprising:a frame; front and rear wheelsconnected to said frame to movably support the frame on the surface tobe cut; a saw blade mounted on said frame for cutting concrete to apreselected cut depth; an engine mounted on said frame and operativelyconnected to said saw blade; a lifting and depth stop assembly, securelymounted between said front wheels and said frame, including a firstcylinder to raise and lower a front portion of said frame on which saidsaw blade is mounted and a second cylinder to set a minimum height towhich said front portion of said frame is lowered, said minimum heightcorresponding to said desired cut depth; and a depth stop indicator foridentifying a current depth to which said frame portion and saw blade islowered, with respect to a predefined reference level, said depth stopindicator including means for resetting said reference level to anydesired depth.